Using an universal unique identifier (UUID) for encoding metadata is known from the prior art, cf. http://www.jpeg.org/metadata/wgln2600.doc. An UUID is an identifier that is unique in respect to the space of all UUIDs. A UUID can be used for multiple purposes, from tagging objects with an extremely short lifetime, to reliably identifying very persistent objects across a network.
The generation of UUIDs does not require a registration authority for each single identifier. Instead, it requires a unique value over space for each UUID generator. This spatially unique value is specified as an IEEE 802 address, which is usually already applied to network-connected systems. This 48-bit address can be assigned based on an address block obtained through the IEEE registration authority. This UUID specification assumes the availability of an IEEE 802 address, see http://www.opengroup.org/onlinepubs/9629399/apdxa.htm. That specification also discloses algorithms for UUID generators.
Further, patent application EP-A-1372343 shows a method for using UUIDs in the context of streaming applications.